Hi, after receiving SIGXCPU for unexpected context switches in a larger application, I found out that the T_FPU bit does not seem to be recognised on x86 during native task creation. Here is a simple test case, watch out for /proc/xenomai/faults after program start and 5 s later: #include #include float x; void task_func(void *p) { rt_task_sleep(5000000000LL); x = 3.14 + (int)p; } main() { RT_TASK task; mlockall(MCL_CURRENT|MCL_FUTURE); rt_task_spawn(&task, NULL, 0, 40, T_FPU | T_JOINABLE, task_func, 0); rt_task_join(&task); return 0; } Any immediate ideas? Jan